An organic light emitting diode (OLED) display device has many advantages such as large viewing angle, fast response, high contrast, high energy efficiency, good adaptability and so on, and therefore it is used more and more widely.
In the organic light emitting diode display device, each pixel has an organic light emitting diode, and the organic light emitting diode is controlled by a circuit on the array substrate. A basic OLED pixel circuit comprises two thin film transistors (a driving transistor and a switch transistor) and one capacitor (2T1C). In order to eliminate threshold voltage shift existing in the driving transistor, the structure of the organic light emitting diode pixel circuit is usually more complex, for example, as shown in FIG. 1, an OLED pixel circuit comprises six thin film transistors and one capacitor (6T1C).
In addition, with the development of technology, more and more display devices are provided with touch function. So-called in cell touch technology refers to that the touch control circuit is integrated in the pixel circuit, by which the products can be made light and thin, and touch reliability can be improved.
A conventional touch circuit is shown in FIG. 2, wherein the photodiodes can sense light and generate a touch signal (the photodiode can be irradiated by light when no touch occurs, and the light is blocked when a touch occurs); or, another conventional touch circuit is shown in FIG. 3, when a touch occurs, the capacitance value of the sensing capacitor changes, and thereby generating a touch signal.
As described above, the touch circuit typically comprises a plurality of components, and the organic light emitting diode pixel circuit also comprises a plurality of components (e.g. 6T1C), therefore, if the touch circuit is to be integrated into the organic light emitting diode pixel circuit, there will be an excessive number of components in the organic light emitting diode pixel circuit, while the pixel has no space to accommodate so many components (especially with the resolution is increasing, and the pixel size becomes smaller, the problem becomes even more serious), thus it is difficult to apply the in cell touch technology to an organic light emitting diode display device.